Air coming from side of blast?

[FilledWithChill]

I test drove a 2002 Buell Blast yesterday with 2700 miles. I am thinking about getting it. When I started it, it started up only when I pulled on the throttle a little bit, then it would run perfectly. Then i test drove it and it ran just fine with no performance issues and i had a lot of fun, but I noticed that on my right leg I would feel a puff of air everytime the cylinder moved up and down. Is this the carburetor backfiring? Or am I ok to buy this bike

[nipunsharp]

it is backfire, mine had that problem when i start my bike warm, but when i switched to 92 octane, it went away.
It could be the carbeurator though.